Heat exchanger suitable for use as a charge air cooler

ABSTRACT

The invention relates to a component, in particular a heat exchanger, in particular for motor vehicles, having a finned tube block. Preferably, at least one inlet chamber and at least one outlet chamber are provided having walls made of a synthetic resin material possessing a heat- and/or chemical-resistant coating.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] The right of priority under 35 U.S.C. §119(a) is claimed based on German Patent Application No. 101 15 123.3, filed Mar. 27, 2001, the specification, drawings, claims and abstract of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a coolant-guiding device, in particular a heat exchange device, and more particularly to a charge air cooler or coolant cooler suitable for use in motor vehicles.

[0003] The “Shell Lexikon Verbrennungsmotor [Shell Internal Combustion Engine Lexicon]”, Supplement to Automobiltechnische Zeitschrift [Journal of Motor Vehicle Engineering] and Motortechnische Zeitschrift [Journal of Engine Technology], installment 33, discloses a charge air cooler. It consists of a finned tube block which is connected to a charge air inlet chamber and to a charge air outlet chamber. In this heat exchanger, hot charge air from a vehicular internal combustion engine can flow through flat tubes of the finned tube block, where a majority of the heat is transferred to the ambient air via fins disposed between the flat tubes, which are in contact with the ambient air.

[0004] As legislation to regulate exhaust gas becomes more stringent, the thermal demands for the components of charge air coolers are being progressively raised. Materials previously used for the header chambers, such as polyamide, cannot always satisfy these thermal requirements when subjected to the corresponding high internal pressures. At high temperatures, in particular, oxidation processes take place, and these may ultimately result in the destruction of the cooler. The use of metal header chambers, which would withstand the stresses, or of very high-grade specialty plastics is generally ruled out by economic considerations, in view of the substantially higher costs. Accordingly, it is a disadvantage of charge air coolers of the type as that mentioned above that their known configuration will not satisfy the thermal demands required in the future.

[0005] In the case of coolant coolers, plastic components are also used. Examples of these are the water tanks of coolant coolers or heater units, the housings of thermostats or water pumps, and tubes or groups of tubes. Plastic components that carry coolant may be aged by the coolant itself. This process is known as hydrolysis.

SUMMARY OF THE INVENTION

[0006] It is therefore an object of the present invention to provide an improved heat exchange device or, in particular, coolant-carrying or air-carrying components that can be produced economically and at the same time satisfy applicable thermal requirements. These devices and/or components can be employed, for example, as a charge air cooler, a coolant cooler or, for example, as the water tanks of coolant coolers or heater units, the housings of thermostats or water pumps, and/or tubes or groups of tubes.

[0007] In accordance with one aspect of the present invention, there has been provided a heat transfer device, comprising: at least one component for guiding a heat transfer medium, this component comprising a synthetic resin, wherein the synthetic resin component is provided with a surface coating in at least one area. Preferably, the device comprises a heat exchanger for a motor vehicle, comprising a finned tube block and at least one inlet chamber and at least one outlet chamber for a heat transfer medium, wherein at least one of the inlet chamber and the outlet chamber comprises a synthetic resin wall structure provided with a surface coating in at least one area.

[0008] In accordance with another aspect of the invention, there is provided an charge air cooler comprising a heat exchanger as defined above, wherein the coated area comprises a portion in contact with heated charge air.

[0009] In accordance with another aspect of the invention, there is provided a coolant cooler comprising a heat exchanger as defined above, wherein the coated area comprises a portion in contact with hot engine coolant.

[0010] In accordance with another still another aspect of the invention, there is provided a motor vehicle, comprising an engine and at least one heat exchange device, wherein the heat exchange device comprises a device as defined above.

[0011] Further objects, features and advantages of the present invention will become apparent from the detailed description of preferred embodiments that follows, when considered together with the accompanying figures of drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In the drawings:

[0013]FIG. 1 is a perspective view of a header chamber of a charge air cooler; and

[0014]FIG. 2 is a cross-sectional view of the header chamber shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] According to the invention, air-carrying or coolant-carrying parts, such as for example the inlet chamber and/or the outlet chamber for a medium to be cooled or other coolant-carrying parts are made of a synthetic resin material, preferably a thermoplastic material, and the synthetic resin material component is provided with a surface coating, at least in some areas.

[0016] This construction is based on a conventional inlet or outlet chamber design and is therefore very economical. In addition, as a result of an additional surface coating which significantly increases the thermal resistance of the header chamber as a result of its oxidation-inhibiting effect, a heat exchanger, e.g., a charge air cooler, can be produced in a manner that both is acceptable from the economic standpoint and also meets requirements from a thermal performance standpoint. As far as the hydrolysis-reducing effect is concerned, a surface coating such as, for example, a lacquer, can also be used.

[0017] From the standpoint of strength, advantages can also be achieved through such a design, because the conventional materials, such as polyamide, are in general more ductile than high-temperature-resistant materials. These conventional materials can be processed more simply, and the tools necessary for processing are subjected to less wear, as a result of which the service life of the tool is increased.

[0018] The surface coating employed according to the invention is preferably produced using a polysiloxane, an epoxy phenol, a polyamide-imide lacquer or a polyester material and is preferably applied to a base material such as a polyamide. Tests have shown that a surface coating having a thickness of from about 0.001 mm to about 0.1 mm, preferably from about 0.01 mm to about 0.1 mm and particularly preferably from about 0.015 mm to about 0.05 mm is sufficient to bring about significant improvements in thermal tolerance. Relatively thin coatings have the advantage that they are more elastic and do not become brittle as quickly as thicker coatings.

[0019] The invention can be used particularly advantageously in a charge air cooler in order to prevent oxidation of the chamber surface at high charge air temperatures. When the invention is used in a coolant cooler, the cooler can be protected by the surface coating against hydrolysis of the material, and the service life of the cooler can thus be increased.

[0020] An exemplary embodiment of the invention is illustrated in the drawings and described in detail below.

[0021] For illustrative purposes only, the exemplary embodiment of the invention is explained with reference to only one preferred application of the invention, namely, a charge air cooler. According to the invention, however, other components mentioned above are also possible instead of the charge air cooler. Because of the similarities in structure, these other types of components are not shown in detail.

[0022]FIG. 1 shows in perspective view a header chamber 10 of the charge air cooler. This header chamber 10, which represents a charge air inlet chamber, consists of a synthetic resin material, preferably a polyamide. The charge air inlet chamber serves to guide hot charge air 12 from a vehicle internal combustion engine to a finned tube block (not shown) and to distribute it uniformly over the tubes. It could also be produced in a similar or identical design as a charge air exit chamber. A finned tube block for heat exchangers is conventional and therefore will not be further described here.

[0023] The header chamber 10 has a connector 14, which is connected to a port of the internal combustion engine, and a tube plate connection surface 16, which is in contact with a tube plate or other structure of the finned tube block, either directly or via a seal.

[0024]FIG. 2 shows a cross-sectional view through the header chamber 10 shown in FIG. 1. It can be seen that the inwardly-oriented surface of the header chamber 10 is provided with an oxidation control coating 18. The oxidation control coating 18 preferably is comprised of a polysiloxane, an epoxy phenol, a polyamide-imide lacquer or a polyester material. The header chamber itself comprises, for example, a material of the type that is conventionally used for header tanks, preferably a polyamide or the like.

[0025] Tests have shown that preferred base materials are polyamide, such as, for example, nylon 66 (N66-GF30) with a glass fiber content of 30% by weight for resistance to temperatures of up to 160° C., polyphthalamide such as PPA-GF40 (polyphthalamide) with a glass fiber content of up to 40% by weight for temperatures up to 200° C., and polyphenylene sulfide, such as PPS-GF40 (polyphenylene sulfide) again with a glass fiber content of 40% by weight for temperatures above 200° C. Instead of the glass fiber contents indicated, other additions in other percentages or fibers of carbon or other materials may be used. Alternatively, an amorphous material such as polyaryl ether sulfone (PES) or polyether imide (PEI) may be used as the based material. Many other base materials are also known and will not be mentioned here. In addition, new base materials may be developed in the future that can equally well benefit from the present invention.

[0026] Examples of suitable materials for the surface coating include, among preferred embodiments, a polyester material (U04KD004 from BASF AG). The following materials are also suitable for the coating: partly crystalline materials such as polyaryl ether ketone (PEEK), polyphthalamide (PPA) and a partly aromatic polyamide (such as for example PA6T) or liquid-crystalline polymer (LCP).

[0027] Any conventional coating process may be used to coat the header chambers or other heat exchange device surfaces with the surface coating material according to the invention. It is preferable, however, to use a spray-coating, dip-coating or spread-coating process. Processes such as CVD, PVD, dusting and electrocoating processes may also be employed advantageously.

[0028] The foregoing description of preferred embodiments of the invention has been presented for purposes of illustration and description only. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible and/or would be apparent in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and that the claims encompass all embodiments of the invention, including the disclosed embodiments and their equivalents. 

What is claimed is:
 1. A heat transfer device, comprising: at least one component for guiding a heat transfer medium, said component being comprised of a synthetic resin, wherein the synthetic resin component is provided with a surface coating in at least one area.
 2. The device as claimed in claim 1, wherein the device comprises a heat exchanger for a motor vehicle, comprising a finned tube block and at least one inlet chamber and at least one outlet chamber for a heat transfer medium, wherein at least one of the inlet chamber and the outlet chamber comprises a synthetic resin wall structure provided with a surface coating in at least one area.
 3. The device as claimed in claim 1, wherein the surface coating comprises an oxidation control coating.
 4. The device as claimed in claim 1, wherein the synthetic resin comprises a polyphthalamide (PPA), a polyphenylene sulfide (PPS) or a polyamide (PA).
 5. The device as claimed in claim 4, wherein the synthetic resin includes at least one reinforcing agent.
 6. The device as claimed in claim 5, wherein the reinforcing agent comprises glass fibers and/or carbon fibers.
 7. The device as claimed in claim 1, wherein the synthetic resin comprises an amorphous material selected from a polyaryl ether sulfone (PES), a polyether imide (PEI) or a polycarbonate (PC).
 8. The device as claimed in claim 1, wherein the surface coating comprises a polysiloxane, a polyester material or a partly crystalline material selected from a polyaryl ether ketone (PEEK), PPA, PA6T or a liquid-crystalline polymer (LCP).
 9. The device as claimed in claim 1, wherein the surface coating has a coating thickness of from about 0.001 mm to about 0.1 mm.
 10. The device as claimed in claim 9, wherein the surface coating has a coating thickness of from about 0.01 mm to about 0.1 mm.
 11. The device as claimed in claim 2, wherein the inlet chamber and the outlet chamber have a wall thickness of from approximately 1.0 mm to 4.5 mm.
 12. The device as claimed in claim 2, wherein the surface coating is present on the inwardly-oriented surface of the inlet chamber and/or of the outlet chamber.
 13. The device as claimed in claim 2, wherein the surface coating is present on the inwardly-oriented surface and the outwardly-oriented surface of the inlet chamber and/or of the outlet chamber.
 14. A process for applying a surface coating to the inlet chamber and/or the outlet chamber of a heat exchanger as claimed in claim 2, comprising applying the surface coating by a spray-coating process or a dip-coating process.
 15. A charge air cooler comprising a heat exchanger as claimed in claim 1, wherein the coated area comprises a portion in contact with heated charge air.
 16. A coolant cooler comprising a heat exchanger as claimed in claim 1, wherein the coated area comprises a portion in contact with hot engine coolant.
 17. A motor vehicle, comprising an engine and at least one heat exchange device, wherein the heat exchange device comprises a device as claimed in claim
 1. 